1. Field of the Invention
The present invention relates to a temperature sensor including a thermistor element, and a manufacturing method for the temperature sensor.
2. Description of the Related Art
In related art, a temperature sensor disclosed in International Publication No. 2008/156082 is one type of temperature sensor. This temperature sensor is manufactured by the following procedure.
First, two lead wires of different lengths are prepared. Next, these lead wires are cut at distal ends thereof. As a result of the cutting, cut surfaces of the respective lead wires are inclined inward to each other, with a metal wire being exposed from the cut surface of each of the lead wires. Next, a thermistor element is disposed so that the side surface of one of the lead wires is attached to the thermistor element in parallel to the longitudinal direction of the thermistor element, and that the distal end of the other lead wire supports a terminal electrode of the thermistor element.
Next, a solder paste is applied to the junction between each of the lead wires and the corresponding terminal electrode. Thereafter, the solder paste is heated with a hot-air heater, causing the solder paste to melt. As a result, the thermistor body is fixed to both of the lead wires.
Next, an insulating member is applied so as to cover the distal end portions of both of the lead wires and the entire thermistor element, and the insulating member is cured. Thereafter, the terminal end portion of each of the lead wires is immersed in a high temperature solder bath, thereby stripping the insulating coat covering this portion, and solder coating is applied.
Through the above steps, the temperature sensor is completed.
In the manufacturing method according to related art, the thermistor element is merely attached to one of the lead wires, and the terminal electrode of the thermistor element is only supported by the distal end of the other lead wire. Therefore, the thermistor element is held by the two lead wires with a relatively weak force. Consequently, at the time of solder paste application or the like, even application of a small external force causes the thermistor element to dislodge from the lead wires. As a result, the percentage of non-defective products (hereinafter, referred to as “yield rate”) is low with the manufacturing method according to related art.